D-glucose and L-leucine metabolism in neonatal and adult cultured rat pancreatic islets.
Neonatal and adult rat islets, cultured for 7-9 days in the presence of 10.5 mM D-glucose, were incubated for 120 min with either D-glucose (2.8 and 16.7 mM) or L-leucine (1.0 and 20.0 mM). The total and anaerobic rates of glycolysis, as judged respectively through the generation of 3H2O from D-[5-3H]glucose and 14C-labelled lactate from D-[3,4-14C]glucose or D-[6-14C]glucose were higher in neonatal than adult islets, but increased to a lesser relative extent in neonatal than adult islets in response to a rise in hexose concentration. The flow through the pentose phosphate pathway, as judged from the difference between D-[1-14C]glucose and D-[6-14C]glucose oxidation was higher in neonatal than adult islets. The flow through the reaction catalyzed by pyruvate dehydrogenase, as judged from the oxidation of D-[3,4-14C]glucose, was lower in neonatal than adult islets incubated in the presence of 16.7 mM (but not 2.8 mM) D-glucose. The oxidation of acetyl residues relative to their generation rate, as judged from the ratio of D-[6-14C]glucose to D-[3,4-14C]glucose oxidation, was not affected by the hexose concentration whether in neonatal or adult islets, but was about twice higher in the latter than former islets. The rate of D-[6-14C]glucose oxidation was also higher in adult than neonatal islets, especially at the high concentration of D-glucose. In both neonatal and adult islets, a rise in hexose concentration stimulated preferentially the oxidation of D[3,4-14C]glucose or D-[6-14C]glucose relative to the utilization of D-[5-3H]glucose.(ABSTRACT TRUNCATED AT 250 WORDS)
Boschero
A C
AC
Department of Physiology and Biophysics, University of Campinas, Brazil.
Bordin
S
S
Sener
A
A
Malaisse
W J
WJ
D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000367:Age Factors; D000693:Anaerobiosis; D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology; D002244:Carbon / Q000378:metabolism; D002478:Cells, Cultured; D002952:Citric Acid Cycle; D003513:Cycloheximide / Q000494:pharmacology; D005947:Glucose / Q000378:metabolism* / Q000494:pharmacology; D006019:Glycolysis; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D007930:Leucine / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats
D007328:Insulin; D002244:Carbon; D000255:Adenosine Triphosphate; D003513:Cycloheximide; D007930:Leucine; D005947:Glucose; D002118:Calcium